Bodies are piling up in Pakistan's largest city as it suffers one of its most violent years in history, and concern is growing that the chaos is giving greater cover for the Taliban to operate and undermining the country's economic epicenter.

Karachi, a sprawling port city on the Arabian Sea, has long been beset by religious, sectarian and ethnic strife. Here armed wings of political parties battle for control of the city, Sunnis and Shiites die in tit-for-tat sectarian killings, and Taliban gunmen attack banks and kill police officers. With an election due next year, the violence could easily worsen.